Preheat oven to 350°.
Unroll rolls; press 2 rolls onto bottom and sides of each of four 5-inch tart pans (or use 4 rolls in each of two 6 1/2-inch quiche pans).
Sprinkle half the onion and all the meat among pans.
Top with cheese.
Mix eggs, milk, mustard, parsley, and 1/4 teaspoon salt.
Pour over cheese.
Place pans on baking sheet.
Bake in 350° oven 20 minutes.
Top with remaining onion during last 5 minutes.